Incandescing electric lamp



(No Model.)

T. A. EDISON.

INOANDBSOING ELECTRIC LAMP.

No. 274,294.- PatentedMar.20,1883.

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THOMAS A. EDISON, OF MENLO PARK, NEW JERSEY.

INCANDESCING 'ELEC TRIC LAMP.

SPECIFIQATION forming part of Letters Patent No. 274,294, dated March 20, 1883.

Application filed November 23, 1882. (No model.)

To all whom it may concern;

Be it known that I, THOMAS A. EDISON, of Menlo Park, in the county of Middlesex and State of New Jersey, have invented a new and useful Improvement in lncandescing Electric Lamps, (Case No. 515,) of which the following is aspecification.

The object I have in viewis to producefiexh ble carbon filaments for the incandescing conductors of electric lamps which shall be of high resistance and of even resistance throughout theirlength, and shall have great flexibility and toughness, so that'they will not be liable to be fractured by the expansion and contraction, more or less unequal, which take place from the lighting and extinguishing of the lamp.

To this end my invention consists in an incandescin g conductor for an electric lamp, formed ofa number of fine continuous filaments massed together, so as to be in close contact throughout the whole length, and having their ends secured, the said individual filaments being capable of independent expansion and contraction throughout the length of their bodies, between the ends, where they are brought together into solid and homogeneous masses. y

In carrying out my invention I preferably take several long and very fine fibers of the same or almost the same length such as those of ramee,fiax, and similar vegetable substances-and twist them tightly together, so as to form a fibrousthread. The ends are secured preferably by a plastic carbonizable substance attached to them, such as a compound of carbon andsugar. The filamentthusformed is carbonized understrain or pressure, or both, and may be bent, either before or after carbonization, into the desired form. The plastic compound upon the ends of the filament may form enlarged ends for clamping. The separate filaments are not secured together by carbonization, but remain free, except at their ends, where they become solid homogeneous masses of carbon. The ends of the twisted filament are then attached to the leading-in wires sealed in the stem or tube of a lamp,

| length. Instead of the process described, the

fibers may be carbonized straight and separate] y, and such carbonized fibers then twisted tightly together. The ends are then attachedtothe leading-in wires, preferably by electroplating, the fibers being kept tightly twisted during this process. The filament formed in either of the above ways and attached to the leading-in wires is placed in the globe of a lampin the usual manner, and is ready for the exhausting process.

While, as stated, I prefer to use natural vegetable fibers, itis evident that a conductor of the kind described may be formed of other substances-such as cellulose, paper, parchment, fine thread treated with hydrofluoric acid, &c.-fine filaments of such substances being twisted together, as described. It will be understood that the fiber is reduced to cellulose before the separate filaments are massed together, in order to maintain the individuality of the separate filament-s after carbonization. Filaments may, it is evident, be braided or intertwined instead of twisted together.

Filaments formed as described are of unusually even resistance and incandescence, as

each of the fibers is continuous, extending the whole length of the filament. The filamentis also exceedingly fiexible'and elastic, and therefore well adapted for the purpose for which it is to be used. The expansion and contraction of the solid carbon filament which take place during theme of the lampare more or less anequal, and for this reason it is liable to be fractured; but by the use of a carbon'filament made up of a number of separate filaments capable of independent expansion and contraction this dang er is greatly diminished.

In the accompanying drawings, Figure 1 is a view of an incandescing electric lamp embodying my invention; and Fig. 2 represents a portionof the twisted filament, the size thereof being of course greatly exaggerated.

A is the inclosing globe, and B the inner, stem, through'which pass'the leading-in wires 1 2, to which are attached the ends of the carbon filament O, which is formed of a number of individual fibers, o c, twisted together, and

stance, a.

What I claim isa 1. A flexible carbon filament for the incantoo secured together at their ends by a plastic subdescing conductor of an electric lamp, formed of a number of separate continuous flexible carbon filaments massed together, substantially as set forth. p

2. A flexible carbon filament for the incandescing conductor of an electric lamp, formed of a number of continuous individual carbonized natural fibers massed together, substantially as set forth.

3. A filament for forming, on carbonization, theincandescingconductor of an electric lamp, consisting of a number of separate filaments, of carbonizable material, massed together, and secured at their ends by a plastic carbonizable compound, substantially as set forth.

4. A flexible carbon filament for incandescing electric lamps, formed of a number of separate flexible carbon filaments with their ends connected in solid homogeneous masses, substantially as set forth.

5. The combination,in an incandescingelectrio lamp, of a chamber made entirely of glass, leading-in wires passing through and sealed in the glass of said chamber, and a flexible carbon incandescing conductor formed of a number of separate filaments massed together and secured to said leading-in Wires, substantially as set forth.

This specification signed and witnessed this 13th day of November, 1882. i

THOS. A. EDISON. Witnesses H. W. SEELY,

EDWARD H. PYATT. 

